Motorized handpiece



June 23, 1936. H. A. WHITESIDE `MOTORIZED HANDPIECE Filed April 16, 1934 Howard A. W/n'esme Patented June 23, 1936 UNITEDLA STATES PATENT OFFICE MOTORIZED HANDPIECE Howard A. Whiteside, New York, N. Y. Application April 16, 1934, Serial No. 720,839

3 Claims.

The present invention relates to motorized hand pieces and more particularly to such devices as are suitable for being held in the hand while performing dental or surgical operations or other delicate work.

Surgical and dental engines `and similar tools employ a hand piece consisting essentially of a stationary sheath adapted to be held between the thumb and finger tips of one handa-nd a rotatableA shaft carried in the sheath. rIhe outerend of the shaft is connected to `a tool and the rear end to a source of power, such-.asa driving shaft or spindle. VThe sheath oi' the hand piece is detachably secured to the bearing device for the driving shaft or spindlet Where the-engine is 4of the belt driven type, the coupling device includes-a slip joint and means to carry the pulleyfor driving the spindle or shaft; and where the engine has the flexible shaft type of drive, the coupling device is connected to the sheath aboutthe llexible-shaft. When assembled,these hand-pieces and coupling devices form a rigid unit which extends from in front of the finger tips to'vback ofvtheknuckle so that this rigid unit may be grasped in the hand and'manipulated thereby; --It was thus necessary to have the hand piece and small diameter part of the coupling atleast six inches long. l 1

Suggestions have been advanced-by Vthe Vpresent applicant andbyV others for the direct'connection of an electric motor Ato Athe-hand piece or slip joint, and the-following patents are representative of such suggestions:

Sargent, 776,204, November 2919Q4;"Shelton, 1,201,262, October,` 17, l9.16;Whiteside, ;13189,184, June '16, 1916; Whitesidefjl'l-JZBS, June, 1926; Whiteside, 1,836,350, Decemberfil, 1931, vReference to these patents will-show thatthehand pieces andlcoupling devices were of such length and diameter that, when `heldin the hand, the motor was disposed behind the knuckle. To develop adequate torque, the motors were made Vof considerably larger diameter than the hand piece and coupling, and were made las'short as possible to conserve weight and length, vandvfacilitate han,- dling. In these constructions-the hand-pieces and coupling weigh 3A; ounce to 3 ounces and the'motors from fibunces to 12 ounces,tandhence .the `center of gravity in all suchlmotori/zed toolunits must be in the motor and therefore to the rear of the knuckles. Y n

According to the present invention, the motorizedtool unit is designedlas an entity for the `use to which it is intended. The length `of the hand-piece -andlcoupli-ng-.are reduced and the niotor is made of much smaller diameter and longer. The tool units contemplated by the present invention may be grasped between the thumb and fingertips in the usual way and the motor rests on the interdigital space between the thumb and index finger.

The rear end of the unit projects a short distance behind the knuckle, but the center of gravity of the unit is near the lower or front end of the motor, Hence, the unit has no tendency to overturn as is present in the motorized tool units having long hand pieces and overhanging motors.`

I have also found that these units may be held or gripped much more securely with less eiort. Should the operator relax the grip on the former type of unit, the heavy motor would drag the unit out of the hand, causing it to drop. Relaxing the grip on the improved form of construction does notrelease the unit. It rests in the hand loosely, like a pencil which is nottightly gripped. The motor diameter is larger than the diameter of the usual hand piece and ts into the space between the index finger knuckle and thumb knuckle in such a way as to reduce the amount of rolling or traveling of the unit owing to its tendency to pivot about the gripping point. is easier for the operator to see around the instrument and work in restricted spaces as there is no large motorV body to interfere with vision'. Also the tendency of the former type mechanism to castV shadows on the work is almost entirely eliminated. A further advantage of the long, small diameter motor is the elimination of noticeable gyroscopic effect. The large diameter of the armatures of the overhanging motors introduced a very noticeably gyroscopc eiTect, especially at high speeds, and this interferes'with the shifting of the tool to a. new position.

Other and further objects of the present invention will appear as the description proceeds.

The accompanying drawing shows, for purposes of illustrating the present invention, one of the many embodiments in which the invention Vmay take form, it being understood that the drawing is illustrative of the inventionrrather than` limiting the same. In the drawing:

' Figure 1 is aperspective view illustratingthe luse of the motorized tool unit held in the hand;

Figure 2 is a longitudinal sectional view through the rear end ofthe motor and taken on the linev 2-2 of Fig. 4;

' Figure `3 is a longitudinal sectional view through a hand piece connected to the motor;

Figure 4 is an elevational View of the end cap "for the motor; andV Figure 5 is a section on the line 5-5 of Figure 3.

The motorized tool unit utilizes a motor A and a hand piece or tool holder B. A tool, such as a grindstone is shown at C. The entire unit is held in the hand after the fashion of a pencil, the thumb and fingertips gripping the sheath of the hand piece and the motor extending rearwardly between the thumb and index nger of the hand, and a short distance beyond the index finger knuckle. The motor may have an overall length of about l1/2 inches and an outside diameter of 'M3 of an inch to 1 inch, and weigh complete 4% to 6 ounces. The hand piece may be about 2% inches long, and weigh about 2 ounces. The center of gravity of the hand piece is indicated at b and is practically at the gripping point. The center of gravity of the motor unit is indicated at a and is about 21/4 inches to the rear of the joint where these parts are coupled. Hence, the center of gravity of the complete unit is somewhat closer to the coupling or at approximately the point ab. As a result of these factors, the center of gravity of the complete unit is well below (or in front of) the knuckle joint or may be said to be adjacent the second or middle joint of the index finger and the first joint of the thumb, as will be clearly understood.

Figures 2, 3, and 4 illlustrate in detail a suitable embodiment of motor and hand piece whereby the advantages of the present arrangement may be had in practice. It will, of course, be understood that these details may be varied and the major objectives above referred to obtained, so long as the length diameter of parts and mass distribution are kept within a proper range.

The motor a has a cup shaped casing I preferably made of one piece of insulating material. This casing carries the field structure of the motor and supports the bearing for the armature shaft.

An insulating brush rigging disc II extends across the open end of the casing IU. The disc tI has a reduced portion I2 which telescopically iits into the casing I6 and small screws I3 secure the disc in place. The disc II is provided with a tubular bearing member I4 for the adjacent end I5 of the armature shaft. The disc I I also carries two tubes I6 which constitute brush boxes (only one of these brush boxes appears in the drawing). The brush boxes I6 are threaded as indicated at I1 to fit threaded holes in the disc I I and are locked in place by threaded rings I8. Each brush box is threaded as indicated at I9 to receive a screw 20. The brush and brush spring are indicated at 2I and 22 respectively.

The disc II also carries a pair of conducting pins 23 adapted to act as field connections. Each pin is threaded through a hole 24 in the disc and is locked in place by a nut 25.

The end cap of the motor is indicated at 26. It is also made of insulating material and is cup shaped so as to telescope over the brush rigging disc II, its end abutting against the end of the casing I0. Two threaded inserts 21-21 are threaded into the end cap. These inserts are tubular as indicated and are split as shown at 28. They are spaced the same as the brush boxes I6 and are such a size as to grip the brush boxes when the parts are assembled. A second pair of tubular inserts 29-29 is also carried by the end cap. These inserts are spaced the same as the pins 23 and are split so as .to grip them. The current supply wires are brought in by a four conductor cord 30 and the separate wires, 30a, 30h, 30e, 30d, soldered to the inserts 28 and 29 as indicated. The end cap is drilled as indicated at 32 to receive screws 33 which are threaded into tapped holes in the screws 26 so that the 5 end cap is firmly secured to the disc II.

The commutator, as indicated at 34, is close to the disc I I so that the brushes may bear on it. The front end IUa of the motor casing I0 is reduced as indicated in the drawing and is provided with an internally threaded bore 35 to receive a threaded bushing 36 preferably made of stainless steel. The bushing is shouldered as indicated at 36' to abut against the end of the insulating casing Ia and locking screws 31 se- 15 cure these two parts together. The metal bushing 36 carries insulating bushing 38 which in turn supports a phosphor-bronze bearing 39 for the front end 40 of the armature shaft. The shaft is drilled from the outer end to receive an insulating insert 4I and this insert is then provided with a non-circular opening 42. The armature shaft 40 has a shoulder 43 which en gages with the end of the bearing 39 to take the thrust caused by the brush springs 22.

'Ihe metal bushing 36 is internally threaded as indicated at 44 to receive the hand piece. The hand piece is shown in detail in Figures 3 and 5.

It is provided with a coupling member 50 externally threaded at 5I to cooperate with threads 30 44. The other end of the coupling is threaded as indicated at 52 to cooperate with the threads 53 on a sheath 54. This sheath, at the front, has a tapered bearing indicated at 55 to accommodate the tapered end 56 of a spindle 51. This 35 spindle extends throughout the length of the sheath. The rear end is reduced and flattened as indicated at 58, to t the non-circular opening 42. Any other suitable form of driving connection may be used.

The spindle is made in two parts, these parts being threaded together as indicated at 60. The left or front part is drilled to accommodate a tool clutch 6I of usual construction, and this tool clutch is adapted to be operated by a two part plunger 62, these parts being threaded together as indicated at 63. The left part of the plunger is provided with a slot 64 to permit adjusting the plunger parts by inserting a screw driver through the clutch. The plunger is prevented from rotating by a pin 63 which is guided in a slot 66 in the inner end of the spindle. The plunger 62 is operated by a lever 61 pivoted at 68 and under the control of a sliding ring 69 carrying a cam 10 cooperative with the serrated edge 55 1I of the lever 61.

The slidable sleeve 69 moves back and forth on the outside of the spindle and is prevented from rotating by the cam 10 secured to it and entering a transverse slot 61' in the spindle part, 60 this slot being made to accommodate the lever 61. The sleeve is moved back and forth by a slider 12 which has a projection 13 adapted to enter an annular recess 14 in the sleeve 69.

The slider 12 is held in place by a stationary 65 outer covering for the sheath. This outer covering comprises two parts 15 and 16, each of which is made up of an outer ring 15 and an inner incomplete ring 15" open at 15"' to accommodate the slider 12. The ring member 16 is similar to the one 15, except that it is longer and is provided with a slot 16 to accommodate the thumb piece 11 secured to the slider 12. Reciprocating this thumb piece 11 back and forth will actuate 75 The inward thrust of the tool and spindle is l taken up by the left or inner end of the spindle which engages with an adjustable bushing 80 carried in threads in the inside of the coupling member 50. This bushing may be adjusted accurately and locked in place by a lock ring 8| indicated in Figure 3. In this manner it is possible to design and provide a hand piece of short, compact nature suitable for use with a short Inotor or for use with other forms of dental engine. The two part plunger 62 may be adjusted to take up the wear in the clutch and the bearing 80 may be adjusted to take up Wear between the spindle and the sleeve or sheath.

The organization which has been described may be handled very easily by the surgeon or dentist. The entire device is so light as not to tire the operator. The operator can actuate the clutch release 'l1 by the nger or thumb without using the other hand. A tool can be released in this same manner and another tool picked up from a support without necessarily touching the tool to insert the shank of the tool into the hand piece. This organization also has the advantage over many forms of hand piece which require the extending of the hand piece to lengthen it when lthe tool is clutched.

Owing to the small diameter of the motor armature, there is no noticeable gyroscopic effect` even at high speeds, and owing to the small diameter of the motor, there is nothing to obstruct vision such as is the case with large overhanging motors.

This application is a continuation, in part, of application iil'ed March 19, 1930, Serial No. 437,154.

It is obvious that the invention may be embodied in many forms and constructions and I wish it to be known that the particular form shown is but one of the many forms. Various modications and changes being possible, I do not otherwise limit myself in any way with respect thereto.

What is claimed is:

1. An electric engine comprising a direct connected electric motor and hand piece in axial alignment, the front end of the engine being adapted to be gripped between the thumb and lirst and second iingers of the hand with the hand piece extending forwardly of the tip of the thumb and lingers and the motor extending rear-V wardly over the thumb-index finger interdigital space and a short distance beyond the knuckle of the index nger, whereby the engine may be held in the hand after the fashion of a pencil, the. hand piece being short and compact so that its rear end is adjacent the gripping point and having a stationary sheath, a rotatable shaft and l5 a releasable clutch to secure a tool to the shaft, the electric motor having a small diameter cylindrical casing rigidly secured to the hand piece sheath and an armature shaft drivingly *connected with the hand piece shaft, the mass of the motor being distributed throughout the length of the same, the diameter of the casing being such that the casing substantially lls the space between the index finger knuckle joint and the thumb knuckle joint so as to reduce its range of movement when the tool is applied to the work, the center of gravity of the combined motor and hand piece being in the forward end of the motor so as to fall in front ofthe first index finger knuckle joint, whereby the engine rests against the thumb-index nger interdigital space without tendency to overturn.

2. An engine as claimed in claim 1, wherein the releasable clutch of the hand piece has an oper' ating member disposed adjacent the rear end of the hand piece for manipulation by the thumb or finger while the engine is held in the hand as set forth.

3. An engine as claimed in claim 1, characterized in that the hand piece is of the same length when clutched to a tool as when released so that the position of the center of gravity of the organization is not altered sensibly by the addition of the tool.

HOWARD A. WHITESIDE. 

